• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.4
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• pp.21-28
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• 2014

Daily use characteristics of apparent power supplied to distribution transformer can be separated into two different time zone of waking hours and sleeping hours. In sleeping hours, using amount of power is decreasing. The actual curve of power seemed to be quite similar to this kind of separation. Inserting a condenser into a circuit in each different time zone led to maximize power factor of the transformer. The compensating condenser's on/off time is controlled by hysteresis circuit utilizing op amp and power factor of the transformer was improved from 0.945 to 0.999. As a result, the average of current reduction was 2.53A per hour of transformer.

• Journal of Communications and Networks
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• v.11 no.4
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• pp.406-415
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• 2009

In this work, we consider performance modeling of a wireless sensor network with a time division multiple access (TDMA) media access protocol with slot reuse. It is assumed that all the nodes are peers of each other and they have two modes of operation, active and sleep modes. We model the sensor network as a Jackson network with unreliable nodes with on and off states. Active and sleep modes of sensor nodes are modeled with on and off states of unreliable nodes. We determine the joint distribution of the sensor node queue lengths in the network. From this result, we derive the probability distribution of the number of active nodes and blocking probability of node activation. Then, we present the mean packet delay, average sleep period of a node and the network throughput. We present numerical results as well as simulation results to verify the analysis. Finally, we discuss how the derived results may be used in the design of sensor networks.

• Journal of Communications and Networks
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• v.18 no.2
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• pp.246-260
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• 2016

A major challenge achieving scalable access control for a large number of subscribers in a public broadcast is to distribute key update messages reliably to all stateless receivers. However, in a public broadcast, the rekeying messages can be dropped or compromised during transmission over an insecure broadcast channel, or transmitted to receivers while they were off-line. In this study, we propose a novel group key management scheme. It features a mechanism to allow legitimate receivers to recover the current group key, even if they lose key update messages for long-term sessions. The scheme uses short hint messages and member computation. Performance analysis shows that the proposed scheme has the advantages of scalability and efficient rekeying compared to previous reliable group key distribution schemes. The proposed key management scheme targets a conditional access system in a media broadcast in which there is no feedback channel from receivers to the broadcasting station.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.12 no.2
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• pp.205-211
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• 1999

We studied 32 patents, who had visited Kyung Hee downtown oriental hospital with nasal obstruction. They has been observed their nasal cavity through anterior rhinoscopy. We had paten't middle and inferior turbinte bleeding by acupuncture. This symptom had been disappeared after this treatment. The result were as follows. 1. Sex and age distribution: The males were 18($56.2\%) and Female were 14($43.8\%$). The most common occurrence was found between 1-5 years old. 2. The most common duration of disease was between 2-6 months. 3. In decreasing order, the common complication & past history of otolaryngologic or allergic disease were allergic rhinitis, atopic dermatitis, chronic sinusitis, adenoid or tonsil hypertrophy, otitis media with effusion and asthma. 4. In descending order, distribution of symptoms were rhinorrhea, sneezing, dry sensation, sputum, frontal headach, postnasal drip and cough. 5. The improvement rate in symptom were $31.3\%\;excellent\;and\;53.1\%$ good.

• Steel and Composite Structures
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• v.38 no.2
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• pp.141-150
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• 2021

In the present paper we have investigated the Stoneley wave propagation at the interface of two dissimilar homogeneous nonlocal magneto-thermoelastic media under the effect of hall current applied to multi-dual-phase lag heat transfer. The secular equations of Stoneley waves have been derived by using appropriate boundary conditions. The wave characteristics such as attenuation coefficients, temperature distribution and phase velocity are computed and have been depicted graphically. Effect of nonlocal parameter and hall effect are studied on the attenuation coefficient, phase velocity, temperature distribution change, stress component and displacement component. Also, some particular cases have been discussed from the present study.

• Journal of the Semiconductor & Display Technology
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• v.20 no.1
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• pp.42-47
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• 2021

In this study, we developed an application that can efficiently store and manage food ingredients in refrigerators. Rather than purchasing a new smart refrigerator, a small 'pocket scanner' is inserted inside the refrigerator using an existing refrigerator to track the location of food entering and leaving the refrigerator to efficiently organize the refrigerator and save time searching for ingredients. In addition, since it can automatically record the distribution period and purchase date, it notifies users through an alarm when the distribution period expires or is shortly left. As for the research method, after discovering the needs of users through in-depth interviews, the reactions of users were investigated by adding functions that fit those needs. Users felt satisfied with managing food efficiently through the 'pocket scanner' attached to the refrigerator and answered that it was very economical because various smart functions could be used without changing to a smart refrigerator. In the next study, we will also examine the usability of the application through usability evaluation.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.21 no.3
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• pp.231-239
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• 1999

In oral and maxillofacial surgery, there are many cases requiring the graft of epidermal tissues such as maxillectomy, and vestibuloplasty. There have been so many challenges for the culture of the epidermal tissue. Observing the ultrastructure of the cultured human oral kertinocytes, we could compare this findings with that of in vivo ones. With that, we could find the differencies and similarities between cultured cells and in vivo ones, and evaluate the clinical applications of cultured tissue. Human gingiva was obtained and the specimen was explanted on 24-well plate. Two types of culture media were used in this culture system. One was for the growth of the keratinocytes (Media I), and the other was for the stratification (Media II). Media I had special ingredients for the epidermal growth. Those were 0.5% dimethyl sulfoxide (DMSO), 30ng/ml of epidermal growth factor (EGF), 30ng/ml of cholera toxin, and $5{\mu}g/ml$ of transferrin. We cultured the oral keratinocytes for 3 weeks, and at that time the cultured keratinocytes were processed to prepare the specimen for the TEM study. The results were as follows.; 1. In the phase contrast micrograph, epidermal outgrowth firstly appeared on the 3rd day after explantation, and the growing keratinocytes were activley mitotic, and had polygonal shape and increased N/C ratio. 2. In the phase contrast micrograph, the outer most cells exhibited areas where broad cytoplasmic processes extended out onto the culture subtratum(fan-like appaearance). 3. In the TEM micrographs, the cultured keratinocytes showed stratification. The cells were in elongated form, and there were no morphologic differencies among the layers usually found in the in vivo gingiva. 4. Most of cellular organelles underwent lysis, and keratohyaline granules were seen. Tonofibrils were dispersed in the cytoplasm. 5. The cells were interconnected by desmosomes, and their frequency of distribution was considered to be lower than that of in vivo keratinocytes. 6. We could conclude the cultured oral keratinocytes exhibited signs of terminal differentiation.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.160-165
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• 1999

Agarose gels can be used as reference standards for the measurement of fluid properties in porous media because the relaxation properties of the gel reference standard and those of the fluid in porous media can be closely matched. The use of reference standard to determine porosity and saturation is discussed and the requirements for gel NMR properties given. The relaxtion times of agarose gels measured at 2.0 Tesla are illustrated as a function of agarose and paramagnetic impurity ($CuSO_4$) concentrations. This work shows an empirical result between agarose gel composition and gel relaxtion times. The average value for the porosity distribution is 17.7%, which compares well with the value calculated with the gravimetric analysis. Finally, two phase immiscible displacement using agarose gels as a reference standard was performed. The saturation profiles appear to be consistent with what one might calculate for a one-dimensional displacement in a uniform porous media.

• The Journal of Art Theory & Practice
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• no.2
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• pp.121-146
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• 2004

Compared to the influences of Korean art journalism, the researches on them are rarely conducted. This study aims to examine the influence of art journalism in art magazines in Korea. Although it is essential to consider media, journalism, public opinion altogether, I focused only on the media due to the absence of previous studies I have analyzed the current conditions of korean art journalism, types of feature articles, sponsors, their relations with articles and the comparison with foreign art journalism in terms of production conditions. There have been about one hundred art magazines published in previous sixty years and currently there are twenty three. Monthly periodicals are the majority: the publishers are sorted out as publishing houses, galleries, newspaper company in order specialized art magazines developed from the eighties. Through an examination of feature articles in these art magazines, I found that they repeated similar art issues and covered the same artists sponsors and articles. Moreover, when the magazines went through the conflicts between managers and editors, the ascendency of managers obstructed the development of art journalism regarding journal quality. These days, art journalism have been comparatively regressed compared to other art systems such as art museums, curatorship, international aft festivals, distributions and art promotion policies. The main causes for failure were the lack of professional management, the limited effort to diversify sponsors, and the repetition of the same informants and events without making an effort to be specialized Magazines are published media which contribute to the creation of culture, distribution, and preservation. Therefore art magazines can be said the most influential media in forming art culture and distributing it. It is quite necessary to reform the problems of repeating of information and the lack of speciality in conjunction with the commitment of management and editorialship.

• Journal of the Korea Computer Graphics Society
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• v.18 no.3
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• pp.29-35
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• 2012

As the distribution rate of the Smart mobile increased, the software technology and ideas for the ubiquitous systems advanced day after day to establish an environment where the public can easily access and experience such technologies. The communication between an individual and the many became more convenient through the social network services (SNS) and the individuals started to attempt to communicate in various methods. The communication methods and techniques became more diverse and the media art pieces focusing on the communications among many also became more interesting. This study attempted to create a prototype of the visual communication media art through the indirect participation of one of the widespread SNS, Twitter, for the communication and also to suggest the direct and indirect communication routes among the humans. In addition, the use of the typography in the pieces also attempted to examine a new type of work that combines the SNS and media art while delivering the text messages.